We are using the isoenzymes of aldolase as a model system to investigate, in detail, the regulation of specific protein synthesis in animal cells. The synthesis of the three aldolase subunit types A, B, and C, are independently regulated. We are using cell-free protein synthesis systems to correlate the rates of synthesis of the subunit types in vivo with the levels of polysomes and mRNAs coding for the aldolases. The regulation of aldolase synthesis in tissues of developing, adult, aging, and diseased (diabetic, dystrophic) animals is being investigated. BIBLIOGRAPHIC REFERENCES: Lebherz, H.G. (1976). Polysomal RNA directed synthesis of aldolase tetramers in a simplified cell-free system. Fed. Proc. 35, 1567. Lebherz, H.G. (1976). Studies on the regulation of aldolase subunit synthesis and subunit assembly in a heterologous cell-free system. 10th International Congr. Biochem. Hamburg. (Abstracts) p. 132.